Example embodiments of the inventive concepts described herein relate to a semiconductor memory and/or a method of operating the same. For example, at least some example embodiments relate to an operation method of a memory controller and/or an operation method of a storage device.
Semiconductor memory devices are classified into volatile memory devices, which lose data stored therein at power-off, such as a static random access memory (SRAM), a dynamic RAM (DRAM), a synchronous DRAM (SDRAM), and the like, and nonvolatile memory devices, which retain data stored therein even at power-off, such as a read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory device, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), and the like.
The flash memory device stores data by setting the threshold voltages of memory cells. However, as a time elapses, the threshold voltages of the memory cells may vary due to various factors. In the case where threshold voltages of the memory cells vary, data stored in the flash memory device may not be identified normally. That is, the change in the threshold voltages of the memory cells may cause a decrease in reliability of data stored in the flash memory device.